Did You Know? Some people report a fishy smell after supplementing with L carnitine. This happens because certain gut bacteria convert carnitine to trimethylamine, a malodorous compound found in rotting fish. L Carnitine: Benefits, Uses, Side Effects, and More Govinda Lifecare A recurring fishy odor could indicate a larger medical problem. Does Carnitine Cause Body Odor? Lume Deodorant If you always smell sweaty, sour, or like onions, you need to check your gut because most body odor starts inside; constipation, yeast overgrowth, and poor bile flow create toxic sweat, so